Buffing device.



L.- V. LEWIS. BUEPING DEVICE. APPLmATmiI FILED JA'N.11,1912.

Patented Aug. 19, 1913.

' INVENTOR 062 74 fofwa FIG. 1

d [1 6 ATTORNEY COLUMBIA PLANOGRAFH C0..WASHINGTON. n, c.

UNITED STATES PATENT OFFICE.

LLOYD V. LEWIS, F EDGEWOOD PARK, PENNSYLVANIA, ASSIGNOR TO THE UNIONSWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A CORPORATION OFPENNSYLVANIA.

BUFFING DEVICE.

Specification of Letters Patent.

Patented Aug. 19,1913.

, To all whom it may concern:

Be it known that I, LLOYD V. LEwIs, a citizen of the United States,residing at Edgewood Park, in the county of Allegheny and State ofPennsylvania, have invented certain new and useful Improvements inBufling Devices, of which the following is a specification.

My invention relates to bufiing devices for absorbing the momentum ofmoving parts. A buffing device embodying my invention is particularlyadapted for absorbing the momentum of the moving parts in a relay of thevane type, although its use is not limited to this particularapplication.

I will describe one form of buffing device embodying my invention andthen point out the novel features thereof in claims.

In the accompanying drawings, Figure l is a View showing in sideelevation a relay having applied thereto one form of buffing deviceembodying my invention. Figs. 2 and 3 are views showing in side and endelevation respectively, and on a larger scale, the bufling device shownin Fig. 1.

Similar reference characters refer to similar parts in each of theseveral views.

One feature of a buifing device embodying my invention is the provisionof a movable weight or buiiing member which is constrained by guides tomovement in an inclined path. This weight normally rests at the lowestpoint of the path due to the action of gravity, but when it is engagedby a moving body whose momentum is to be absorbed it is moved upwardlyin this path. During this upward movement the momentum of the movingbody is gradually absorbed both by the work done in raising the weightagainst gravity and by the friction between the weight and its guides.

Referring to the accompanying drawings, the buffing device as here showncomprises a U-shaped frame-work 10 mounted with its sides in verticalplanes. In these upright sides are out two slots 11, directly oppositeto each other and inclined from the horizontal. As here shown theseslots are slightly curved upwardly, but this specific shape of the slotsalthough preferable, is not essential to my invention. These slots serveas guides for a shaft 12 which is mounted to move freely in the slots,and upon which is rigidly mounted a roller 12. This shaft and rollertaken together constitnte a bufling member or weight, which normallyrests at the lowest point of the slots due to the action of gravity, butwhich is moved upwardly when engaged by a moving body.

Referring now particularly to Fig. 1, the relay here shown comprises avane 14 of aluminum or other suitable material pivotally mounted at 15.This vane moves between the polepieces of a soft iron core 16 upon whichare mounted one or more energizing windings 17. The vane is biased bygravity or otherwise to its lowest position, indicated by dash lines,but when the winding 17 is properly energized by alternating current thevane is rotated upwardly to the position in which it is shown in fulllines.

18 is an oscillating shaft which carries contact members 19 and 20; thisshaft is connected with the vane by means of a crank 21 and a link 22eccentrically pinned to the vane, the connections being so arranged thatwhen the vane occupies the position indicated in full lines, the frontcontact 20 is closed as shown, and when the vane occupies the lowestposition of its stroke the back contact 19 will be closed and frontcontact 20 open.

When the energizing current in winding 17 is out off or sutlicientlyreduced, the vane 14 will rotate downwardly under the influence ofgravity. As here shown, a bufling device embodying my invention isemployed for arresting the rotation of the vane when it reaches thelowest point of its stroke. The position of the lower edge of the vanewhen it strikes the roller 13 is indicated in dash lines in the drawing.The momentum of the vane and of the moving parts moves the roller andshaft upwardly in the slots, the momentum being gradually absorbed bythe work done in raising the weight and by the friction between theshaft and the lower edges of the slots. This friction is of aconsiderable amount owing to the fact that the weight is prevented fromrotating, be-

cause of the difierence between the radius of the roller against whichthe vane presses and the radius of the shaft which moves in the slots.If the buffing device is properly proportioned to the momentum of themoving parts, the movement of the vane will be completely arrestedbefore the weight has reached the upper end of the slots, and the partswill then either rest in such position or will move slowly backwarduntil the weight reaches the lower end of the slots.

If the vane l4c has any tendency to sustain oscillations of graduallydecreasing amplitude, this tendency will be counteracted by the bufiingdevice embodying my invention, because this bufling device is incapableof sustaining oscillatory motion.

The reason for this is that the bufling weight;

moves in the two different directions-that is, up and down,attwodifferent speeds, and the reason for this last fact is as follows: Sincethe roller 13 is larger in diameter than its shaft 12, when a drivingforce is applied in the direction shown by the arrow in the drawing,that is, in a radial direction, the roller and shaft are constrained toslide in the guides without rotation. The energy of the driving member(the vane) is, therefore, consumed partly in friction, the remainderbeing transformed into potential energy by raising the weight againstgravity. On the return or downward movement, the roller and shaft willrotate, and not slide, because then the only force be tween the rollerand the vane is that due to the force of gravity, there being no forcedue to the deceleration of the vane, hence the force between these twomembers is considerably less than it was on the upward stroke; andbecause the inclination of the guide slots 11 is such as not to exceedthe angle of repose of the roller and shaft with reference to the lineof gravity. Hence, the downward stroke is accomplished at acomparatively slow speed, and only a small portion of the potentialenergy stored up in the weight is returned to the vane, the greaterportion being transformed into kinetic energy of rotation of the rollerand into heat due to friction between the roller and the vane. 7

From the},f0regoing it will be seen that any tendency of the vanetooscillate will be immediately counteracted by the bufling deviceembodying my invention, and that there will, therefore, be no chatteringof the contacts operated by the vane.

In the preferred embodiment of my invention, the slots 11 are curvedgradually upward, the lower ends being only slightly inclined from thehorizontal, as shown in the drawings. hen constructed in this mannertheinertia of rest of the weight is overcome by moving the weight in analmost horizontal direction, so that the friction between the shaft andthe slots is a minimum during the early part of the movement, and sothat during this part of the movement the weight is being raised veryslowly against gravity. Then as the weight is moved farther along in theslots it begins to rise, so that the angle between the line of movementand the horizontal plane constantly increases, hence the work to be doneconstantly increases. This work consists in raising the weight againstgravity, and in overcoming the friction between the weight and theslots. The increase in work done in raising the weight against gravityas the above-mentioned angle increases is due to the fact that thevertical component of the movement 0f the weight for a given angularmovement of the relay vane constantly increases; and the increase ofwork done in overcoming friction is due to the fact that as theabove-mentioned angle increases, the line of force between the vane andthe weight constantly becomes more nearly at right angles to the lowersurface of the guiding slots. Hence, it will be seen that because of thecurvature of the guiding slots, the force acting in opposition to themovement of the vane is at first very small, and constantly increases,so that the vane is brought to rest without shock.

By means of a bufling device embodying my invention, the momentum of themoving parts is absorbed without sudden shock. There is therefore notendency for chattering brought to rest, and all danger of injury to thevane and moving parts connected therewith owing to sudden stoppage isavoided.

Although I have herein shown and described only one form of buffingdevice embodying my invention, it is understood that various changes andmodifications may be made therein within the scope of the appendedclaims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is 1. In combination, amovable body whose momentum is to be absorbed; and a bufling devicecomprising two upright walls, oppositely disposed and parallel inclinedslots in said walls, a shaft adapted to move freely in said slots, and aroller mounted upon the shaft and located in the path of said body.

2. In combination, a movable body whose momentum is to be absorbed; anda buffing device comprising a weight adapted to be raised by said body,and means for constraining said weight to movement in a path curvedupwardly from the horizontal whereby the resistance offered by theweight is at first small and increases as the weight is moved upwardly,so that the movement of the body is arrested without shock.

In testimony whereof I affix my signature in presence of two witnesses.V

LLOYD V. LEWIS. Witnesses:

A. L. VnNoiLL, ME'NA QUEALE.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents,

Washington, D. G.

of the contacts when the vane is.

